Soaking water functional properties

Abstract

The soaking water of legumes containd soluble and insoluble carbohydrates, protein, minerals, phenolic and saponins. These compounds are known to improve food texture and act as prebiotics. Therefore, this chapter presents new findings on legume soaking water as texturizer (freeze-dried) and prebiotic (liquid). The low fractions of soluble carbohydrates and proteins resulted in modest foaming ability (4.0–19%), modest oil absorption capacity (2.1–2.7 g/g) and insignificant effects on water absorption. In contrast, excellent emulsifying ability was observed for split yellow peas (50 m2/g), with relevant values for green lentils and yellow soybeans. Different mechanisms have been proposed: presence of both soluble and insoluble proteins (peas), saponins (lentils) and amphiphilic proteins (soy). Remarkably, prebiotic properties were observed in liquid samples. The growth of probiotic Lactobacillioccurred to levels drastically higher than a standard nutrient broth. Oligosaccharides were abundant in haricot beans, while higher biological value of soy proteins might explain soy performance. Results of lentils and peas were lower than other legume. Antimicrobial peptides known as defensin Psd1, Psd2 (peas) and Lc-def (lentils) might have inhibited microbial growth. In summary, lentil soaking water can be freeze-dried into excellent emulsifiers, especially peas. Beans and soy soaking water are also promising prebiotics.